Effects of hydrosaline treatments on prolyl endopeptidase activity in rat tissues

Enzymatic cleavage of some peptide hormones, neurotransmitters and neuromodulators could be implicated in the regulation of extra- and intracellular fluid volume and osmolality. Prolyl endopeptidase is known to hydrolyze several peptides, which act on hydromineral balance, such as angiotensins, bradykinin, vasopressin, oxytocin, thyrotropin-releasing hormone, neurotensin and opioids. In this work, we analyzed the effects of certain volume and/or osmotic changes in the activity of the soluble and membrane-bound prolyl endopeptidase in several brain areas, heart, lungs, kidney and adrenal and pituitary glands of the rat. Soluble prolyl endopeptidase activity was higher in the renal cortex of the chronic salt-loaded rats than in the control rats. In the water-deprived and polyethylene glycol-treated rats, heart particulate prolyl endopeptidase was lower than in the control rats. Particulate prolyl endopeptidase was also lower in the adrenal gland of the acute salt-loaded rats and in the brain cortex of the water-loaded rats than in the control rats. Data suggest that tissue-dependent peptide hydrolysis evoked by prolyl endopeptidase activity is involved in the water-electrolyte homeostasis.     

Natural enemies of Coelomera lanio (Coleoptera: Chrysomelidae) in the region of Viçosa,Minas Gerais,Brazil

Coelomera lanio (Coleoptera: Chrysomelidae) is the most important defoliator of Cecropia trees. Natural enemies of C. lanio collected in the region of Vi?osa, State of Minas Gerais, Brazil were identified on field observations in a forest fragment and on laboratory analyses. Individuals of C. lanio were not found on Cecropia pachystachya trees colonized by Azteca mülleri (Hymenoptera: Formicidae). The majority of the egg masses of C. lanio collected in the field were found to be parasitised by a species of the family Eulophidae (Hymenoptera), while larvae of this pest were attacked by a parasitoid of the family Tachinidae (Diptera). Individuals of Oplomus catena (Heteroptera: Pentatomidae) were observed preying on C. lanio larvae. The fungus Beauveria bassiana was found growing on larvae, pupae and adults of C. lanio while the fungus Metarhizium anisopliae only affected pupae of this insect in laboratory conditions.     

Evaluation of filamentous fungi and inducers for the production of endo-polygalacturonase by solid state fermentation

Aspergillus oryzae CCT 3940, Aspergillus awamori NRRL 3112 and a Trichoderma sp.) were compared for their capacity to produce endo-polygalacturonase (endo-PG) in solid state fermentation. Maximum pectinolytic activity was reached in 72 h of growth, the best two fungal strains being A. niger T0005007-2 and A. oryzae CCT 3940. Three types of commercial purified pectin and four of unprocessed pectin (tangerine, orange, Tahiti lime and sweet lime rind) were used to assess the effect of pectin on the production of endo-PG by A. niger T0005007-2. Maximum pectinolytic activity was achieved using 6 and 10% (w/w) of purified pectin as inducer. Depending on the origin of the commercial pectin used as inducer, maximum endo-PG levels varied from 223 to 876 units per gram of dry medium (one endo-PG unit (U) was defined as the quantity of enzyme which caused a reduction in viscosity of 50% in a 1% w/v solution of pectin in 30 min), indicating that care should be taken when choosing this component of the medium. When the crude pectins were used as inducers at the same concentration as purified pectin, maximum endo-PG activities were 250-300 units/g. However, by increasing the amount of Tahiti lime rind to 50% (w/w) maximum endo-PG was 919 U/g, thus opening up the possibility of a low cost medium for endo-PG production.     

Membrane fluidity adjustments in ethanol-stressed Oenococcus oeni cells

The effect of ethanol on the cytoplasmic membrane of Oenococcus oeni cells and the role of membrane changes in the acquired tolerance to ethanol were investigated. Membrane tolerance to ethanol was defined as the resistance to ethanol-induced leakage of preloaded carboxyfluorescein (cF) from cells. To probe the fluidity of the cytoplasmic membrane, intact cells were labeled with doxyl-stearic acids and analyzed by electron spin resonance spectroscopy. Although the effect of ethanol was noticeable across the width of the membrane, we focused on fluidity changes at the lipid-water interface. Fluidity increased with increasing concentrations of ethanol. Cells responded to growth in the presence of 8% (vol/vol) ethanol by decreasing fluidity. Upon exposure to a range of ethanol concentrations, these adapted cells had reduced fluidity and cF leakage compared with cells grown in the absence of ethanol. Analysis of the membrane composition revealed an increase in the degree of fatty acid unsaturation and a decrease in the total amount of lipids in the cells grown in the presence of 8% (vol/vol) ethanol. Preexposure for 2 h to 12% (vol/vol) ethanol also reduced membrane fluidity and cF leakage. This short-term adaptation was not prevented in the presence of chloramphenicol, suggesting that de novo protein synthesis was not involved. We found a strong correlation between fluidity and cF leakage for all treatments and alcohol concentrations tested. We propose that the protective effect of growth in the presence of ethanol is, to a large extent, based on modification of the physicochemical state of the membrane, i.e., cells adjust their membrane permeability by decreasing fluidity at the lipid-water interface.     

Chromosomal polymorphism,syntenic relationships,and ploidy in the pathogenic fungus Paracoccidioides brasiliensis

Pulsed field gel electrophoresis (PFGE) and DNA hybridization were used to establish and compare the electrophoretic karyotypes of 12 clinical and environmental Paracoccidioides brasiliensis isolates from different geographic areas. Gene mapping allowed the identification of synteny groups and the use of isolated whole chromosomal bands to probe chromoblots indicated the existence of repetitive sequences, contributing to a better understanding of the structure and organization of the fungus genome. This represents the first comparative mapping study among different isolates. The results are indicative of the existence of genetic differences among natural isolates. DNA content of DAPI-stained nuclei of each isolate was estimated by confocal microscopy. Comparison of the genome sizes estimated by PFGE with those calculated by microfluorometry indicated the possible existence of haploid and diploid (or aneuploid) isolates of the fungus.     

Antiproliferative effects of several compounds isolated from Amburana cearensis A. C. Smith

Amburana cearensis a common tree found in Northeastern Brazil is widely used in folk medicine. The present work evaluated the cytotoxicity of kaempferol, isokaempferide, amburoside A and protocatechuic acid isolated from the ethanol extract of the trunk bark of A. cearensis. The compounds were tested for their cytotoxicity on the sea urchin egg development, hemolysis assay and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay using tumor cell lines. Isokaempferide and kaempferol, but not amburoside A and protocatechuic acid, inhibited the sea urchin egg development as well as tumor cell lines, but in this assay isokaempferide was more potent than kaempferol. Protocatechuic acid was the only compound able to induce hemolysis of mouse erythrocytes, suggesting that the cytotoxicity of kaempferol and isokaempeferide was not related to membrane damage.     

Prevention of diseases caused by Staphylococcus aureus using the peptide RIP

Staphylococcus aureus causes many diseases including cellulitis, keratitis, osteomyelitis, septic arthritis and mastitis. The heptapeptide RIP has been shown to prevent cellulitis in mice, which was induced by S. aureus strain Smith diffuse. Here we show that RIP can also significantly reduce the overall pathology and delay the onset of disease symptoms in several other models of S. aureus infections, including: keratitis (tested in rabbits against S. aureus 8325-4), osteomyelitis (tested in rabbits against S. aureus MS), mastitis (tested in cows against S. aureus Newbould 305, AE-1, and environmental infections) and septic arthritis (tested in mice against S. aureus LS-1). These findings substantiate that RIP is not strain specific in its inhibitory activity and that RIP is an effective inhibitor of bacterial pathology at multiple body sites following diverse routes and doses of administration. These findings strongly evidence the potential value of RIP as a chemotherapeutic agent.     

Effect of Chronic Variate Stress on Thiobarbituric-Acid Reactive Species and on Total Radical-Trapping Potential in Distinct Regions of Rat Brain

It has been suggested that oxidative stress is involved in aging and neuropathologic disorders. In addition, chronic stress and high corticosterone levels are suggested to induce neuronal death. The aim of this study is to verify the effect of chronic variate stress on lipoperoxidation and on the total radical-trapping potential (TRAP) in hippocampus, hypothalamus and cerebral cortex. Adult male Wistar rats were submitted to different stressors during 40 days. Lipid peroxide levels were assessed by the thiobarbituric acid reactive species (TBARS) reaction, and TRAP was measured by the decrease in luminescence using the 2-2-azo-bis(2-amidinopropane)-luminol system. The results showed that in cerebral cortex homogenates chronic stress induces an increase in oxidative stress. In hypothalamus a decreased lipoperoxidation was observed, however TRAP showed no difference. In hippocampus no difference was observed. We concluded that prolonged stress induces oxidative stress which varies selectively with the brain region.     

Monitoring the domiciliary and peridomiciliary invasion process of Triatoma rubrovaria in the State of Rio Grande do Sul, Brazil

The presence of Triatoma rubrovaria in Brazil has only been confirmed in the States of Paraná and Rio Grande do Sul (RS), where it is found naturally infected with Trypanosoma cruzi. In the wild environment it occurs in rocky habitats and has an eclectic diet, feeding from cockroaches, reptiles and mammals. Data from the Chagas Disease Control Program obtained by the Funda??o Nacional de Saúde, between 1975 and 1997, indicate a growing domiciliary and peridomiciliary invasion of T. rubrovaria in RS, where it has become the most frequently Triatominae species captured in this state since the control of Triatoma infestans. In order to monitor this process, we analyzed collection data derived from 22 years of control campaigns against T. infestans. Collection data for triatomines from domestic habitats show an inverse relationship, with high numbers of T. infestans and low numbers of T. rubrovaria during 1976-1987, compared to the following ten years, 1986-1997, when the number of T. infestans dropped drastically and that of T. rubrovaria increased. There are no consistent indications of intradomiciliary colonization by T. rubrovaria, since only low numbers of nymphs have been captured in the intradomiciliary ecotopes. Nevertheless, this species appears to have preadaptive characteristics for anthropic ecotopes, and should be kept under constant epidemiological surveillance.     

Ultrastructure of muscle cells from a few selected turbellarians: possible correlations between form and function

A comparative ultrastructural study of muscle cells from several turbellarian species revealed a basic smooth type of construction, with thick and thin myofilaments. However, the distribution of contractile elements, "dense bodies", smooth reticulum, mitochondria, as well as junctional specializations was found to vary within different systems. This variability is probably related to greater or lesser physical demands on the musculature. From a mechanical viewpoint, the most ‘powerful’ muscular system studied was represented by the pharyngeal bulb of Geocentrophora applanata, in which muscle fibers were organized into a compact, square reticulum, hemidesmosomes occurred in large numbers, and myofilaments were grouped in patches reminiscent of A and I bands of striated muscles. At the other extreme, muscular fibrils of the catenulids studied were thin and regularly spaced along the body wall, and the branched ends of radial myofibrils in the parenchyma were connected to the epithelial layer. This revised version was published online in July 2006 with corrections to the Cover Date.